International migration has long been a central tool in the battle against global poverty and inequality, but the recent heated political debate over immigration reform has largely failed to recognize how migration shapes the development process. In this essay, research fellow Michael Clemens and co-author Sami Bazzi outline five major reasons why migration is a development issue in today’s world, and they suggest an agenda for the next U.S. administration to make U.S. migration policy work for the United States, for countries of origin, and for the migrants themselves.